---
layout: docs
page_title: Agent Sidecar Injector Installation
sidebar_title: Installation
description: The Vault Agent Sidecar Injector can be installed using Vault Helm.
---

# Installing the Agent Injector

The [Vault Helm chart](/docs/platform/k8s/helm) is the recommended way to
install and configure the Agent Injector in Kubernetes.

~> The Vault Agent Injector requires Vault 1.3.1 or greater.

To install a new instance of Vault and the Vault Agent Injector, first add the
Hashicorp helm repository and ensure you have access to the chart:

```shell-session
$ helm repo add hashicorp https://helm.releases.hashicorp.com
"hashicorp" has been added to your repositories

$ helm search repo hashicorp/vault
NAME           	CHART VERSION	APP VERSION	DESCRIPTION
hashicorp/vault	0.9.0        	1.6.1      	Official HashiCorp Vault Chart
```

Then install the chart and enable the injection feature by setting the
`injector.enabled` value to `true`:

```bash
helm install vault hashicorp/vault --set="injector.enabled=true"
```

Upgrades may be performed with `helm upgrade` on an existing install. Please
always run Helm with `--dry-run` before any install or upgrade to verify
changes.

You can see all the available values settings by running `helm inspect values hashicorp/vault` or by reading the [Vault Helm Configuration
Docs](/docs/platform/k8s/helm/configuration). Commonly used values in the Helm
chart include limiting the namespaces the injector runs in, TLS options and
more.

## TLS Options

Admission webhook controllers require TLS to run within Kubernetes. At this time
the Vault Agent Injector supports two TLS options:

- Auto TLS generation (default)
- Manual TLS

### Auto TLS

By default, the Vault Agent Injector will bootstrap TLS by generating a certificate
authority and creating a certificate/key to be used by the controller. If using
Vault Helm, the chart will automatically create the necessary DNS entries for the
controller's service used to verify the certificate.

### Manual TLS

If desired, users can supply their own TLS certificates, key and certificate authority.
The following is required to configure TLS manually:

- Server certificate/key
- Base64 PEM encoded Certificate Authority bundle

For more information on configuring manual TLS, see the [Vault Helm cert values](/docs/platform/k8s/helm/configuration#certs).

## Multiple Replicas and TLS

The Vault Agent Injector can be run with multiple replicas if using [Manual
TLS](#manual-tls), and as of v0.7.0 multiple replicas are also supported with
[Auto TLS](#auto-tls). The number of replicas is controlled in the Vault Helm
chart by the [injector.replicas
value](/docs/platform/k8s/helm/configuration#replicas).

With Auto TLS and multiple replicas, a leader-elector sidecar container is
deployed with each replica. These sidecars determine which injector replica is
the "leader" in charge of generating the CA and patching the webhook caBundle in
Kubernetes, and also generating and distributing the certificate and key to the
"followers". The followers read the certificate and key needed for the webhook
service listener from a Kubernetes Secret, which is updated by the leader when a
certificate is near expiration.

The leader-elector sidecar in use is described in detail [here][k8s-blog]. For
more information on configuring leader election, see the [Vault Helm
leaderElector values](/docs/platform/k8s/helm/configuration#leaderelector).

With Manual TLS and multiple replicas,
[injector.leaderElector.enabled](/docs/platform/k8s/helm/configuration#enabled-2)
should be set to `false` since leader-election is not necessary in this case.

If there is only one replica set (regardless of other TLS or leaderElector
settings), no leader-elector containers will be deployed.

[k8s-blog]: <https://kubernetes.io/blog/2016/01/simple-leader-election-with-kubernetes/> "Simple leader election with Kubernetes and Docker"

## Namespace Selector

By default, the Vault Agent Injector will process all namespaces in Kubernetes except
the system namespaces `kube-system` and `kube-public`. To limit what namespaces
the injector can work in a namespace selector can be defined to match labels attached
to namespaces.

For more information on configuring namespace selection, see the [Vault Helm namespaceSelector value](/docs/platform/k8s/helm/configuration#namespaceselector).
